Your Digest for Sunday, Jan 07, 2024 03:59 PM


Broadly, lymphoma is distinguished from leukaemia in its clinical presentation, where lymphoma predominately involves lymph nodes, and leukaemia the blood and bone marrow, and by the fact that lymphomas arise from cells that reside in the lymphatic system rather than in the bone marrow. However, in the context of the cell of origin this is perhaps a rather nebulous distinction, and there is evidence that chronic lymphocytic leukaemia (CLL) may emerge in differentiated/mature lymphocytes in the periphery
[!INFO] The correct identification of AML vs ALL is veryimportant as a determines treatment.

AML ALL
Diverse Group of diseases
Proliferation of myeloid blasts Lymphoid blasts
clonal proliferation of myeloid precursors with a reduced capacity to differentiate into more mature cellular elements.
As a result, there is an accumulation of leukemic blasts or immature forms in the bone marrow, peripheral blood
NCNC anaemia, ⬇ Platelets
Blasts infiltrate bone marrow
NCNC anaemia, ⬇ Platelets
Symptoms: pancytopaenic symptoms: anemia, bleeding, and an increased risk of infection. Bone pain is uncommon; Fever = Infection! Similar
Bone pain can be presenting complaint in children (and adults)?
CNV involvement less CNS invovelemt more common
No / Less lymphadenopathy Lymphadenopathy more predominant
Presentation as Tissue mass is less common Can present as thymic or testicular masses
Gum hypertrophy, Skin involvement and CNS disease occur in myelomonocytic and monocytic types
Commonest adult acute leukemia (80% of cases) - 65 years Occurs in children.
Accounst for only 10% of paediatric leukemia
About 1.5x commoner in males
De novo OR in backdrop of preexisting myelodysplasia OR cytotoxic medication Acquired mutations leading to formation of BCR-ABL fusion gene (among others) (via 9;22 translocation)
Assoc. with trisomy 21; Fanconi anemia;
Auer rods seen Auer rods never seen.
Myeloblast have finer chromatin and more cytoplasm.
Cells are peroxidase positive.
Lymphoblasts have course chromatin
Cells are PAS positive
negative. Immunophenotyping: Terminal deoxynucleotidyl trasnferase (TdT) positive
Increased risk of DIC (in promyelocytic variant) Increased risk of Tumour lysis syndrome
"devastating"; poor prognosis Good prognosis (esp in t(12:21))
Good prognosis:
t[8:21], inv[16]
bad prognosis:
Presence of MLL rearrangements, Presence of BCR-ABL fusion gene t(9:22), t(4:11), hypoploidy

Note : T cells are the commonest type of lymphocytes in healthy states, followed by B and NK cells.

  1. outside the usual age range (i.e worse prognosis if pt is infant or adolescent) because tumours with good prognosis karyotypes (t[12:21] and hyperploidy) are commoner in this age group.
  2. Male gender
  3. Philadelphia chromosome positive
  4. Slow response to induction therapy (i.e more than 28 days)- (? children usually respond fast to induction therapy?)
  5. Having Trisomy 21.

atypicalLymphocytesinMononucleosis.png

EBV / mononucleosis ALL
Teens 4 year olds
Atypical lymphocytes Blast cells
Acute disease course Acute disease course
Splenomegaly and lymphadenopathy hepatosplenomegaly and lymphadenopathy
Lymphocytosis Lymphocytotis with anaemia and thrombocytopaenia
Not present Clinical feature of cell line suppression including mucosal bleeds
Several long term complications: lymphoma, multiple sclerosis, chronic EBV infection, nasopharyngeal CA and others
Very high WBC indicates ALL (but WBC can be low or normal in ALL)